package io.File;

import java.util.HashSet;
import java.util.Scanner;

public class SetTest{
    public static void main(String[] args) {
        HashSet<Integer> set = new HashSet<Integer>();
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        for (int i = 0; i < n; i++) {
            set.add(sc.nextInt());
        }
        sc.close();
        if (set.size() < n) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
}
